The sensor mentioned above relates to a photosensor, and the so-called water-proof structure is mainly designed for an outdoor sensor device. The conventional outdoor sensing and lighting device, as shown in FIG. 1, includes a lamp (6), a cell seat (4), an AC electric wire (5), a sensor housing (1) and a rotatable joint (2). Said lighting device is powered through solar energy or AC electric wire (5), and by means of the rotatable sensor (1). If people or a foreign body enters into its detecting area, the lamp (6) will be turned on to light up a specific area for the motion of people or for guarding against burglary, and the lamp (6) will be turned off after the people leave the detecting area. Such power-saving and practical sensing and lighting device is usually used in a staircase, aisle, yard or plaza.
In the aforesaid lighting device, the detecting elements and circuit in the housing of the sensor are all sensitive elements which are liable to be damaged due to humidity which will cause the short-circuit or oxidation of the elements. Since such conventional sensing and lighting device is placed outdoors, it is usually covered and eroded by rain, dew, frost or snow, and the seam of the housing, the wire hole, and rotatable joint are all easily intruded by water which will leak into the housing along the wire and flow onto the circuit board of the sensor. In other words, the conventional structure for the housing of the sensor can not prevent the intrusion of water.